And also, prepare for correct lowering of lifetime. We still don't handle most lifetimes correctly, but a bit more of the foundation to lifetime elision is now implemented.
Also known as E0747 and E0107.
And by the way, rewrite how we lower generic arguments and deduplicate it between paths and method calls. The new version is taken almost straight from rustc.
This commit also changes the binders of `generic_defaults()`, to only include the binders of the arguments up to (and not including) the current argument. This make it easier to handle it in the rewritten lowering of generic args. It's also how rustc does it.
Now that they're const it's no longer needed.
Nothing manual was performed: only a regexp search of `sym::([\w][\w\d]*)\.clone\(\)` and replace by `sym::$1`.
And make more queries non-interned.
Also flip the default for queries, now the default is to not intern and to intern a query you need to say `invoke_interned`.
This refactors how we deal with items in hir-def lowering.
- It now lowers all of them through an "ExpressionStore" (kind of a misnomer as this point) as their so called *Signatures.
- We now uniformly lower type AST into TypeRefs before type inference.
- Likewise, this moves macro expansion out of type inference, resulting in a single place where we do non-defmap macro expansion.
- Finally, this PR removes a lot of information from ItemTree, making the DefMap a lot less likely to be recomputed and have it only depend on actual early name resolution related information (not 100% true, we still have ADT fields in there but thats a follow up removal).
We miss one place: associated type bindings aka. `impl Trait<Type(..): Send>`, but we also miss it for Fn-style parenthesizes error so I left it out for now.
This is required to format evaluated consts, because we need trait env, and it needs the crate (currently it uses the last crate in topological order, which is wrong, the next commit will fix that).
I was wrong on #19127, I thought hir-def resolver is enough for them, but it turns out not because of paths like `<Enum>::Variant` and `Type::AssocThatIsEnum::Variant`.
And add a new diagnostic for non-`Fn` parenthesized generic args.
Path lowering started to look like a mess, with each function carrying additional parameters for the diagnostic callback (since paths can occur both in type and in expression/pattern position, and their diagnostic handling is different) and the segment index, for the diagnostics report. So I refactored it from stateless functions on `TyLoweringContext` into stateful struct, `PathLoweringContext`, that tracks the process of lowering a path from resolution til assoc types selection.
